Electronic device manufacturers strive to produce a rich interface for users. Conventional devices use visual and auditory cues to provide feedback to a user. In some interface devices, kinesthetic feedback (such as active and resistive force feedback) and/or tactile feedback (such as vibration, texture, and heat) is also provided to the user, and may be examples of haptic feedback, or more generally haptic effects. Haptic feedback can provide cues that enhance and simplify the user experience using the user interface. Specifically, vibration effects, or vibrotactile haptic effects, may be useful in providing cues to users of electronic devices to alert the user to specific events, or provide realistic feedback to create greater sensory immersion within a simulated or virtual environment.
Haptic feedback has also been increasingly incorporated in portable electronic devices, such as cellular telephones, personal digital assistants (“PDAs”), portable gaming devices or game controllers, computer tablets, and a variety of other portable electronic devices. Additionally, devices such as cellular telephones and PDAs are capable of providing various alerts to users by way of vibrations. For example, a cellular telephone can alert a user to an incoming telephone call by vibrating. Similarly, a PDA can alert a user to a scheduled calendar item or provide a user with a reminder for a “to do” list item or calendar appointment.
In order to generate vibration effects, some electronic devices use an actuator, such as an Eccentric Rotating Mass (“ERM”) actuator in which an eccentric mass is moved by a motor, a Linear Resonant Actuator (“LRA”) in which a mass attached to a spring is driven back and forth, or an actuator using a “smart material” such as piezoelectric material, electro-active polymers, or shape memory alloys.